What is the government supposed to do with regards to civil liberties?According to the Constitution.

The main thing that the government is supposed to do with
regard to civil liberties is to avoid infringing on them.  In other words, civil
liberties are our right to be free from government interference in our lives. 
Therefore, governments role is to make sure it doesn't violate our civil
liberties.

If you look at the Bill of Rights (where most of
our civil liberties are spelled out), you see that it talks about what the government
must not do, not what it must do.  So when it comes to
civil liberties, government's role is mostly negative.  It must be sure that it does not
prevent us from practicing our religion.  It must be sure that it does not take away our
right to free speech.  It must be sure that its officials do not search us or our houses
without probable cause.

There are a few "positive" things
government can do (like providing poor defendants with a lawyer) with regards to civil
liberties, but mostly it is just supposed to make sure it doesn't infringe on those
liberties.